MONTPELIER — A Brattleboro police sergeant who teaches Vermont police officers on the use of force was himself exonerated of any criminal wrongdoing in the fatal shooting of an unarmed man during an April drug raid, after an investigation by the Vermont attorney general’s office.

A separate review by Bennington County State’s Attorney Erica Marthage came to the same conclusion.

Sgt. Mark Carignan was justified in his use of fatal force in the early morning of April 4 at a Brattleboro motel during the execution of a search warrant, both reports stated.

Carignan shot Michael Santiago, 35, twice with his shotgun after Santiago refused to obey Carignan’s commands to show his hands, according to the attorney general’s release issued Thursday.

Santiago’s female companion, who witnessed the incident, gave an identical version of the morning’s events as Carignan and other officers, the report stated.

Carignan, who was placed on administrative leave immediately after the fatal shooting, had returned to full-time duty with the Brattleboro Police Department on May 26, about seven weeks after the shooting. “I’m pleased with the conclusion of the attorney general’s report,” he said, referring all comment to his attorney, David Williams of Burlington.

Williams said Carignan was an instructor at the Vermont Police Academy on the use of force and when force is justified.

He is not a firearms instructor, Williams said.

Williams, who is representing a Winooski police officer who is being prosecuted by the attorney general’s office for excessive use of force, said the investigation and report were fair.

“Sgt. Carignan was completely cooperative with the police investigation, and he sat down and told the state police what happened. He’s been waiting for a decision,” said Williams.

Assistant Attorney General John Treadwell, head of the criminal division, said a review of the “totality of the circumstances” and a review of what information Carignan had at the time were determining factors in his office’s conclusion.

Santiago had resisted allowing police into his motel room, and then kept his right hand concealed behind his back. He refused Carignan’s orders to show his hand and warned him if he didn’t, he might be shot.

“In response, Santiago advanced towards the officers while moving his right shoulder and arm — an officer described the motion as being consistent with drawing a firearm,” according to the attorney general’s release.

Carignan then shot Santiago twice with his shotgun, the report stated.

Police had been told by other law enforcement agencies that Santiago and his companion, Amanda Piermarini, had recently bought firearms, the report stated.

No weapons were found in the room, and Santiago was unarmed.

Police had a search warrant for Santiago’s person and his room at the America’s Best Inn in Brattleboro and were looking for evidence of drug dealing and to arrest him for violating conditions of release for two pending cases. They found 10 bags of heroin in Santiago’s boxer shorts, as well as $2,000 in cash in a dresser drawer.

Santiago had recently gotten out of jail, and was facing 16 charges in Brattleboro criminal court including a charge of an aggravated assault of a Brattleboro police officer and eight counts of credit card fraud. He also had a pending heroin trafficking case in Burlington.

Marthage said that the critical issue for her in deciding Carignan’s use of force was justified was reviewing the preparation the police officers went through for the search warrant, and the information they received from other law enforcement sources that Santiago had recently bought guns.

Police, before executing the search warrant on Santiago’s room, were very thorough, she said. “This wasn’t something that was quickly decided upon and there were a number of planning sessions,” she said.

It is standard in such cases that police officers carry shotguns, she said.